Semiconductor light emitting devices, such as a light emitting diode (LED), may be provided in a package for protection, color selection, focusing, and the like for light emitted by the device. An LED package generally includes a substrate member on which an LED is mounted. The LED may include a mounting pad attached to the substrate member with electrical connections being made to the LED for applying an electrical bias. LEDs generally comprise an active region of semiconductor material sandwiched between two oppositely doped layers. When a bias is applied across the doped layers, holes and electrons are injected into the active region where they recombine to generate light. Light is emitted omnidirectionally from the active layer and from all surfaces of the LED. The substrate member may also include traces or metal leads for connecting the package to external circuitry and the substrate may also act as a heat sink to conduct heat away from the LED during operation.
An LED package may include a lens positioned for receiving light emitted by an LED in the package. The lens may include optical materials intended to influence or change the nature of the light emitted by the LED. Further, the lens may be suitably shaped for scattering the light and/or otherwise redirecting or influencing the light.
A lens is typically attached to the LED package by use of encapsulant. For example, an LED may be positioned within an opening formed by the LED package. The opening may be filled with encapsulant, and the lens attached to the top of the encapsulant at an open end of the opening. Light generated by the LED may pass through the encapsulant for receipt by the LED.
LED packages are intended to operate in a wide range of environments. Typically, LED packages are expected to operate over a wide range of varying temperatures. One difficulty in current LED packages is that voids form in encapsulant used to attach a lens when operated in varying temperatures. The formation of voids can cause substantial degradation in the quality of light emitted by the LED package. In particular, the void can cause the light passing through the encapsulant to appear non-uniform when emitted from the package. It is desirable to provide improvements in LED packages and techniques used for attaching a lens to an LED package. Particularly, it would be beneficial to provide techniques for minimizing or preventing the formation of voids in encapsulant.
Accordingly, there exists a need for light emitting device packages, LED packages and related methods that provide improvements in the quality of emitted light.